Sealed housings are known which are obtained by sealed assembly of a support and a cover by means of wheel soldering. In this case, the wheel closure requires that the size of the housing be sufficiently large (length and width of more than about 10 mm) to avoid mechanical or electrical interference between the wheels during the closure.
Housings closed in a sealed manner by means of a solder of the eutectic type, for example AuSn, are also known. In this case, soldering methods based on eutectics have the drawback of being carried out at high temperatures of the order of 300° C., which degrades the performance of the electronic functions performed by the components encapsulated by the housing. This is because, by thermoelastic effects, these high temperatures degrade the electronic components which are particularly sensitive to high temperatures and/or the junctions between these components and the housing. Moreover, if the junctions are produced by adhesive bonding, they will be degraded by degassing of the adhesives at these temperatures. Furthermore, when the method is controlled poorly, undesired intermetallic compounds are formed during the soldering, which weakens the solder joint for closing the housing.
Sealed housings obtained by adhesively bonding the support to the cover are also known. The adhesive bonding is easy to carry out, but they have the drawback of not ensuring good sealing of the housing because the organic materials contained in the adhesives are permeable to humidity in the more or less long term.
Sealed housings obtained by assembling the support and the cover by means of sealing glasses are also known. This type of method makes it possible to obtain housings which have good sealing. However, these sealing methods have the drawback of being carried out at high temperatures of the order of 350 to 400° C., which degrades the electronic components to be encapsulated or the junctions between the components and the support.
Housings are furthermore known which are assembled in a sealed manner by creating intermetallic compounds at the interface between the cover and the support. These housings have the advantage of requiring relatively low assembly temperatures (beyond 150° C.) and, once formed, of withstanding higher temperatures (of the order of 200° C.). Assembling a housing on the basis of creating intermetallics, however, has the drawback of requiring complicated means and long fabrication times (several hours). Furthermore, the intermetallics only make it possible to assemble metal housings which have high purity and are compatible with the intermetallics.